HELENA - The U.S. Fish and Wildlife Service has ruled the Montana arctic grayling should be protected, but the fish species won't be listed as endangered or threatened because other species take priority.

The agency said in an advance notice of Wednesday's publication in the Federal Register that the Montana grayling population will be added to the candidates list for protection.

"There are other species in line ahead of the arctic grayling," Mark Wilson, field supervisor of the Montana field office of the Fish and Wildlife Service, said Tuesday. "We find it warranted to be listed, but you basically have to take a number because there are so many other species ahead of it."

The review of the grayling fish was part of a U.S. District Court-approved settlement of a lawsuit filed against the agency by the Center for Biological Diversity, Federation of Fly Fishers and Western Watersheds Project. The settlement called for a decision on the fish's status to be made by Aug. 30.

Noah Greenwald, of the Center for Biological Diversity, said Tuesday the decision once again delays long-overdue protections by putting the fish behind 244 other species awaiting protection. The groups will evaluate the ruling and see whether they can challenge it, he said.

With the research that went into the Fish and Wildlife Service's 86-page review, the agency should take the next step and list the grayling as endangered, he said.

"It seems like a terrible waste of resources. They've done the work to say it warrants listing, but instead of doing that, they've delayed," Greenwald said.

The fish exists in southwest Montana, Alaska and Canada. The Montana population was first recognized as a candidate for protection in 1982, and the status was reaffirmed in 2004. In 2007, the agency decided the Montana population of grayling did not merit protection, prompting the groups to sue.

Grayling used to be found throughout the upper Missouri River drainage but now can only be found in part of the Big Hole river and some lakes in the area, according to the Center for Biological Diversity.

Wilson said it has been hard to get an exact count of the Montana arctic grayling population, but that wildlife officials believe the population is stable and conservation practices are under way to improve its habitat along the Big Hole.

"We don't feel like the arctic grayling is going to blink out tomorrow," Wilson said.